The project is designed to shed information on how such factors as stimulus intensity, unchanged stimulus input, heteromodal stimulation, and sensory threshold task performance differentially affect autonomic nervous system (ANS) functioning in selected personality groups. Examined also is the relative correspondence of bilateral electrodermal activity and its relation to perceptual task performance. Black and white males are sampled in an effort to provide data on racial differences in ANS functioning to imperative and uncontrolled stimulus input.